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go                PRACTICAL  ORGANIC  CHEMISTRY

The distilling flask is provided with a thermometer, ancl attached
to a short condenser and receiver. The receiver consists of a,
second distilling flask, which is tightly attached to the end of the
condenser and connected by the side limb with pump-tubing to
a water-jet aspirator and mercury manometer. Some small
bits of of porous pot are placed in the flask, and the apparatus
exhausted to about 50  60 mm. pressure. The liquid distils at
a nearly constant temperature (about 50  53), and consists of
nearly pure bromacetylbromide. The calculated quantity of
water is added to convert it into bromacetic acid, when the liquid.
forms a solid crystalline mass.*1 It may be purified by distilla-
tion at atmospheric pressure with condenser-tube only, the
portion boiling above 165 being collected separately.

3-CH3.COOH + P + nBr = sCH2Br.COBr + HPO;} + sHBr.

Bromacetyl bromide.

CH2Br.COBr. + H2O = CH2Br.CO.OH + HBr.

Bromacetic acid.

Properties.  Colourless crystals; m. p. 50  51; b. p. 208.
See Appendix, p. 252.

PREPARATION 19.
Grlycocoll (Glycine, Aminoacetic Acid).    CH2

Braconnot, Ann. Chim. Phys., 1820, (2) 13, 114; Perkin,
Duppa, Trans. Chem. Soc., 1859, 11, 22 ; Kraut, Annalen^ 1891,
266, 292.
50 grms. chloracetic acid.
50 c.c. water.
600 c.c. ammonia, 26*5 per cent. (sp. gr. 0*907 at 14).
Fit up the apparatus shown in Fig. 64. It consists of a large
wide-necked bottle, in which the ammonia solution is placed.
The solution is stirred by a mechanical stirrer, rotated by means
of a water-turbine. The solution of the chloracetic acid in 50
c.c. water, is dropped in from a tap-funnel After standing
24 hours the liquid is poured into a flask, ancl the excess of
ammonia is removed by passing in a current of steam, ancl
evaporating at the same time on the water-bath until the last
traces of ammonia disappear. The solution now contains gly-